
//***********************************************
//
//      Filename: pp35.java
//
//        Author: wwb
//        Mails: 1274860621@qq.com
//        Create: 2018-03-20 23:37:01
// Last Modified: 2018-03-20 23:37:01
//***********************************************
     import java.util.Scanner;
      public class pp35
    {
     public static void main(String[]args)
       {
       int x1, x2, y2, y1;
        double line, number;
          
         Scanner scan = new Scanner(System.in);
       
        System.out.print("x1: ");
        x1 = scan.nextInt();
        
        System.out.print("x2: ");
	x2 = scan.nextInt();
        
	System.out.print("y1: ");
	y1 = scan.nextInt();
	
	System.out.print("y1: ");
	y2 = scan.nextInt();
    
       number = Math.pow((x2-x1),2) - Math.pow((y2-y1),2);
       line = Math.sqrt(number);
        System.out.println("line: " + line);
     }
}
